Periorbital dirofilariasis-clinical and imaging findings: live worm on ultrasound

Subconjunctival Dirofilaria masquerading as nodular scleritis

A man in his late 50s presented with a gradually enlarging, painless, reddish mass on the white portion of his left eye for 2 weeks. His best-corrected visual acuity was 20/20 in both eyes. Slit-lamp examination showed a congested, nodular, elevated lesion on the temporal bulbar conjunctiva with two pustule-like elevations. Anterior segment optical coherence tomography showed a subconjunctival solid mass rather than an abscess or a cyst. Scleral deroofing was performed and a long thread-like object resembling a dead worm was identified. The worm was removed intact, and its histopathology confirmed the diagnosis of Dirofilaria Peripheral blood smear did not show any microfilariae. No recurrences or new lesions were observed during the follow-up examinations at 1 and 5 months post-surgery. This case highlights the importance of considering a parasitic aetiology in cases of nodular or infectious scleritis.

Ocular dirofilariasis: A report from Odisha

We report a case of ocular dirofilariasis in a 68-year-old man manifesting as pre-septal abscess with gradually increasing swelling of the left eyelid and near complete ptosis of eye. A live worm was seen wriggling in the lesion while the abscess was being drained and was extracted carefully. Subsequently, it was identified as an adult female Dirofilaria repens worm. The lid edema and swelling resolved and the patient was discharged without any residual complaints.

Animal and Human Dirofilariasis in India and Sri Lanka: A Systematic Review and Meta-Analysis

Dirofilariasis is an emerging vector-borne tropical disease of public health importance that mainly affects humans and dogs. Dirofilaria immitis and D. repens are the two well-documented dirofilariasis-causing filarioid helminths of both medical and veterinary concerns in India and Sri Lanka. This systematic review and meta-analysis aimed to describe and summarize the current evidence of dirofilariasis prevalence and distribution in India and Sri Lanka. Interestingly, D. repens is reported to circulate in both dogs (prevalence of 35.8% (95% CI: 11.23-60.69)) and humans (97% of published case reports) in India and Sri Lanka, but D. immitis is reported to be present in the dog populations in India (prevalence of 9.7% (95% CI: 8.5-11.0%)), and so far, it has not been reported in Sri Lanka. This peculiar distribution of D. immitis and D. repens in the two neighbouring countries could be due to the interaction between the two parasite species, which could affect the pattern of infection of the two worm species in dogs and thus influence the geographical distribution of these two filarial worms. In medical and veterinary practice, histopathology was the most commonly used diagnostic technique (31.3%; 95% CI 2.5-60.2%). The low specificity of histopathology to speciate the various Dirofilaria spp. may lead to misdiagnosis. It was identified in this study that several regions of India and Sri Lanka have not yet been surveyed for dirofilariasis. This limits our understanding of the geographical distribution and interspecies interactions of the two parasites within these countries. Parasite distribution, disease prevalence, and interspecies interactions between the vectors and the host should be targeted for future research.

Human subcutaneous dirofilariasis: the 'migrating' skin tumor

A 46-year-old woman presented with facial pain and discomfort. Diagnosis of subcutaneous dirofilariasis was reached after several months from symptom onset. Dirofilariasis should be suspected, also in non-endemic areas, in patients with a migrating subcutaneous nodule. Plastic surgery is preferred, as the face is often involved.

Pseudo-Tumor of the Epididymis, a Rare Clinical Presentation of Human Dirofilaria repens Infection: a Report of Autochthonous Case of Dirofilariasis in Southwestern Slovakia

PURPOSE

Dirofilariasis caused by the filarial nematode Dirofilaria repens is mainly a disease of dogs and other carnivores. Also, humans can be accidentally infected with this parasite. The infective third-stage filariform larvae are transmitted by various species of mosquitoes. Until this day, a total of 17 human cases caused by D. repens have been diagnosed in Slovakia, 11 subcutaneous, 4 ocular, 1 pulmonary and 1 in the epididymis. The aim of this report was to describe an unusual clinical case of dirofilariasis of the scrotum.

METHODS

Extirpated worm was subjected to the molecular and histological identification. PCR for the amplification of cytochrome oxidase subunit 1 (CO1) was performed using specific D. repens primer pair.

RESULTS

Here we document the 13th case of human dirofilariasis in a 46-year-old man from southwestern Slovakia. Very rare in humans, genital involvement manifests itself as pseudotumor nodule affecting the epididymis. The patient consulted a general practitioner due to a palpable subcutaneous lump in the scrotum. Routine laboratory analysis revealed blood eosinophilia (16.6%). The ultrasound examination was indicated, and subsequently, surgical excision of the right epididymal nodule was performed. On the basis of histological microscopic examination and PCR-based detection, the helminth was identified as Dirofilaria repens. This represents the ninth case of autochthonous dirofilariasis in Slovakia.

CONCLUSIONS

The majority of D. repens infections were recorded in southwestern regions of Slovak Republic, which are considered to be endemic areas for canine dirofilariasis. Our described patient also comes from southwestern part of Slovakia (Topoľníky, Dunajská Streda region).

Imaging Findings of Subcutaneous Human Dirofilariasis

Dirofilariasis is an emerging helminthic zoonosis seldom reported. Humans are accidental hosts and rarely affected. We report a case of dirofilariasis presenting as a subcutaneous nodule in the uncommon location in the thigh with concealed history of dog meat handler. Of the cases published in literature, imaging findings of this disease have been few and far between. In this article, we describe multimodality imaging findings of dirofilariasis in the thigh.

Recent advances on Dirofilaria repens in dogs and humans in Europe

Dirofilaria repens is a nematode affecting domestic and wild canids, transmitted by several species of mosquitoes. It usually causes a non-pathogenic subcutaneous infection in dogs and is the principal agent of human dirofilariosis in the Old World. In the last decades, D. repens has increased in prevalence in areas where it has already been reported and its distribution range has expanded into new areas of Europe, representing a paradigmatic example of an emergent pathogen. Despite its emergence and zoonotic impact, D. repens has received less attention by scientists compared to Dirofilaria immitis. In this review we report the recent advances of D. repens infection in dogs and humans, and transmission by vectors, and discuss possible factors that influence the spread and increase of this zoonotic parasite in Europe. There is evidence that D. repens has spread faster than D. immitis from the endemic areas of southern Europe to northern Europe. Climate change affecting mosquito vectors and the facilitation of pet travel seem to have contributed to this expansion; however, in the authors' opinion, the major factor is likely the rate of undiagnosed dogs continuing to perpetuate the life-cycle of D. repens. Many infected dogs remain undetected due to the subclinical nature of the disease, the lack of rapid and reliable diagnostic tools and the poor knowledge and still low awareness of D. repens in non-endemic areas. Improved diagnostic tools are warranted to bring D. repens diagnosis to the state of D. immitis diagnosis, as well as improved screening of imported dogs and promotion of preventative measures among veterinarians and dog owners. For vector-borne diseases involving pets, veterinarians play a significant role in prevention and should be more aware of their responsibility in reducing the impact of the zoonotic agents. In addition, they should enhance multisectorial collaboration with medical entomologists and the public health experts, under the concept and the actions of One Health-One Medicine.

Dirofilaria repens microfilariae from a human node fine-needle aspirate: a case report

Background

Human dirofilariosis is still a little known infection even in endemic areas. Dirofilariosis is zoonotic infection usually abortive in humans; instead, we report a very rare case (the 4th in the world), the first in Italy, in which at least two infective larvae became mature adults that mated and produced active microfilariae even though they did not reach peripheral blood.

Case presentation

A 30-year-old Italian woman presented with a transient oedematous swelling on the left abdominal wall with a creeping eruption followed by the occurrence of a subcutaneous nodular painless mass in the iliac region. One month later, a similar temporary swelling appeared on the contralateral inguinal region associated with intermittent joint discomfort in both knees. The patient had recently travelled abroad, therefore many possible diagnoses were to be ruled out. Routine laboratory investigations revealed eosinophilia. An ultrasound examination of the iliac swelling evidenced a well-defined cyst with a big filamentous formation in continuous movement. A fine-needle aspiration of the lesion was performed for parasitological, cytological and histological exams. The prompt microscopic examination of the aspired material showed the presence of numerous microfilariae that were initially morphologically attributed to Mansonella ozzardi. Subsequently, the revision of the Giemsa stained film and molecular analyses of the biological material, allowed to identify Dirofilaria repens as etiological agent of infection.

Conclusions

We report of a case in whom microfilariae were detected in fine-needle aspirate of subcutaneous node, without evidence of microfilaraemia, and the infection failed to become fully patent. Therefore we confirm that complete development and fertilization of D. repens worms in human hosts may occur, at variance with what is commonly believed, that Dirofilaria worms cannot fully develop in humans.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1582-3) contains supplementary material, which is available to authorized users.

Image diagnosis of zoonotic onchocercosis by Onchocerca lupi

Onchocerca lupi, a zoonotic nematode infecting the eyes of carnivores, has been increasingly reported in dogs from Europe and the USA. In order to improve the current status of knowledge on this neglected filarioid, diagnostic imaging tools (i.e., ultrasound scan, computed tomography and magnetic resonance imaging) are herein used to diagnose canine onchocercosis in two dogs, which scored positive for O. lupi microfilariae at the skin snip test and to assess the anatomical location of the nematode within the ocular apparatus. Results indicate that ultrasound tools are useful to address the diagnosis of O. lupi in dogs and to evaluate the localization of nodules or cysts containing the adult nematode.

Diagnosis of human nematode infections

Many hundreds of millions of people throughout the world are infected by nematodes found in the intestine or tissues with a high prevalence in developing countries. Despite their frequency and morbidity, these infections, which may affect migrants and travelers, remain difficult to diagnosis even in developed countries. This is primarily due to the variety of clinical signs often associated with a lack of highly sensitive and specific diagnostic tools. Parasitological diagnosis is often difficult to achieve and can neither be applied during the pre-patent period nor for parasitic impasses. Serological diagnosis is frequently hampered by a lack of specificity due to cross-reaction with others helminthes. Molecular biology methods still require optimization. The diagnostic approach applied by a clinician of a suspected nematode infection is based on a vast set of data including patient history and way of life, clinical examination, non-specific biological tests and, when available, specific diagnostic tests.